In recent times, greater emphasis has been placed on national home security and detecting threats to populations. In particular, detecting or sensing the presence of gases, particularly toxic gases, in the environment has become a priority, and a variety of detection systems and devices have been developed in response thereto. The detection of gases is also critical in certain industrial environments, particularly in clean room environments, such as in the production of semiconductors and microprocessors.
Industrial toxic gas monitors, as used e.g., in semiconductor processing, are required to be sensitive to gases at the parts per billion (ppb) level and specific to certain gases. Traditional analyzers are unwieldly with very long analyzing path lengths in order to reliably achieve ppb-level sensitivities. Therefore, a family of analyzers based on color-changing reactions on paper have been developed and accepted in the market. However, these analyzers require reagent bearing paper, which requires replacement of the paper bearing or on which reagent is placed for each subsequent test. Additionally, paper, even non-woven paper, is not an ideal surface on which to place reagents as the surface has a microscopically non-uniform texture.
Accordingly, it is desirable to provide an analyzer for detecting the presence of a gas, particularly a toxic gas, in an environment, which does not require the use of paper or other consumable material as the reagent supporting surface. In addition, it is desirable to provide an analyzer in which at least a portion of the detection apparatus can be positioned beneath and isolated from the reagent supporting surface, so that detection, particularly optical detection, can be performed through the reagent. Other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention.